1. Technical Field
The present invention is directed toward rotary drain and sewer routers having a cable advancable from a rotatable drum containing a supply of the cable and, more particularly, toward a brake for such drain and sewer routers for selectively stopping rotation of the drum.
2. Background Art
One type of widely used rotary drain and sewer router has a wheeled frame for transporting the drain and sewer router. A cable supply drum rotatable about an axis is mounted to the wheeled frame. A supply of an elongate cable for direction into a drain or sewer is contained within the drum and a length of the cable extends from the drum. The cable is attached to the drum so that upon rotation of the drum about its axis the length of cable extending from the drum rotates about its length. An electric motor is also attached to the wheeled frame. A pulley is attached to a drive shaft extending from the electric motor. A belt is looped around the pulley and radially around the periphery of the drum so that upon rotation of the pulley by the motor the belt causes rotation of the drum about its axis. A cable feed apparatus engages the extending length of the cable to feed the cable into or out of the drum as an incident of rotation of the drum about the axis.
When such a rotary drain and sewer router is used to rout a drain, a cutting tool having a number of sharp blades is attached to the extending length of the cable and fed into the drain or sewer. The motor is then turned on and the drum caused to rotate. The cable feed apparatus causes the cable to be fed from the drum into the drain. Typically, the cutting tool will be fed into the drain until an obstruction is encountered, at which time the cutting tool will cut through the obstruction, clearing a passageway in the drain. However, occasionally the cutting tool will encounter an obstruction which it is unable to cut and the cutting tool may become entangled with the obstruction and rotation of the end of the extending length of cable stopped. Even if the motor is immediately stopped the mass of the cable supply drum causes it to continue rotating, notwithstanding frictional forces within the motor tending to slow the rotation of the drum. The continued rotation of the drum under these circumstances creates a torque in the cable which can actually cause the wheeled frame to tip, creating a risk of grievous harm to an operator, the rotary drain and sewer router or equipment in the area until the drum ceases rotating. A related problem is while the torque on the cable may not cause tipping of the wheeled frame, it may cause the drum to rotate in an opposite direction, causing whipping of the protruding length of cable and a potential for harm to an operator. Another related problem is that occasionally the protruding length of cable will become severed as it is fed into a sewer or drain. Should the severing result in the cable leaving the sewer or pipe, the cable will spin and whip uncontrollably, creating a potential for serious harm until the drum is brought to rest.